By George, I think he's got it! You found the valve. It should be the only thing inline between the firewall and the engine.You should be able to order a replacement through NAPA, Auto Zone, Advance, etc. Don't be surprised if it is not a stock item. I've had the best luck with Auto Zone on speed of filling orders and honoring warranties. I like their quality of replacement parts also. Replacement is not difficult; remove from inline of the hose and replacement is the reverse. Be careful to put the valve back on as you found it and not to reverse the vacuum lines feeding it. Also,(not to insult your intelligence, but)make sure to tighted the heater hose clamps well. It may be a good time while you have it apart to check the integrity of your heater hoses and replace them if they look dicey. Why ask for trouble later. Sorry I couldn't get back to you earlier. I just got back froma scale model show I was competing in in Erie and just got on to check the board. Good luck. You can e-mail direct if you want later.